Making Custom Plinth Blocks for Cased Openings
What Are Plinth Blocks and Why Use Them?
Plinth blocks are thick, rectangular pieces of wood or MDF typically positioned at the base of door casings or case openings. They serve both decorative and functional purposes, offering:
Aesthetic Appeal: They create a seamless, professional transition between baseboards and vertical casing.
Practical Coverage: They help conceal gaps, uneven floors, or imperfections where trim pieces meet.
Durability: By adding thickness and support, plinth blocks protect vulnerable areas of trim from wear and damage.
In our case, the custom plinth blocks addressed the gap issue while enhancing the architectural style of our case openings. Let’s dive into the materials, tools, and step-by-step instructions to create these blocks.
Materials and Tools Used
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Poplar S4S Board (2 in. x 8 in. x 6 ft.)
Purchased from Home Depot, this board provided the ideal size and durability for our project.
Ryobi 10-Inch Sliding Compound Miter Saw
This powerful saw ensured precise cuts for each plinth block.
Diablo 10-Inch Fine Finish Saw Blade (D1060X)
Chosen for its smooth, clean cuts and thin kerf design.
MNA Router Bit Set
Used to create the decorative edge on the plinth blocks.
Bosch 1617EVS Router and Bosch RA1171 Router Table
This powerful combo made routing precise and efficient.
3M Pro Grade Precision Sanding Sponge (120 Grit)
Perfect for fine sanding before and after routing.
Step-by-Step Process
Plan
Cut
Router
Sand
Paint
Plan Cut Router Sand Paint
Plan and Measure
We started by measuring the cased openings to determine the exact size of each plinth block. Using a single poplar board, we planned to cut 16 blocks for 4 openings (2 sides), each 7.5 inches tall and 3.5 inches wide.
Cutting the Plinth Blocks
Using the Ryobi miter saw fitted with the Diablo fine finish blade, we cut the board into 16 precise pieces. Even with the kerf, this setup minimized waste, leaving just over 12 inches of extra material from the custom board.
Routing the Edges
For a polished look, we routed three edges (top, left, and right) of each plinth block using the MNA router bit installed in the Bosch router and guided by the Bosch router table.
Sanding and Priming
After routing, we used the 3M sanding sponge to smooth out any rough edges. A coat of primer prepared the blocks for painting.
Painting and Installing
Using Sherwin-Williams Pro Classic paint, we applied two coats for a durable, semi-gloss finish. The blocks were attached with Liquid Nails, wood glue (if wood touched wood), and finish nails (where appropriate) for a secure and seamless look.
Final Touches
After caulking and filling any imperfections, we applied a final coat of paint to blend the blocks perfectly with the surrounding trim.
Key Takeaways and Lessons Learned
Using high-quality tools like the Ryobi miter saw and Bosch router ensured precise cuts and professional finishes.
Custom lumber orders from Home Depot allowed us to maximize efficiency and reduce waste.
Prepping properly with sanding and priming made painting easier and more durable.
